我正在研究这个preinst文件的内容，该脚本在包从Debian归档文件(.deb)文件解压缩之前执行该文件。
脚本代码如下:
#!/bin/bash
set -e
# Automatically added by dh_installinit
if [ "$1" = install ]; then
if [ -d /usr/share/MyApplicationName ]; then
echo "MyApplicationName is just installed"
return 1
fi
rm -Rf $HOME/.config/nautilus-actions/nautilus-actions.conf
rm -Rf $HOME/.local/share/file-manager/actions/*
fi
# End automatically added section
我的第一个问题是关于这一行的:
set -e
我认为脚本的其余部分非常简单:它检查Debian/Ubuntu包管理器是否正在执行安装操作。如果是，它将检查我的应用程序是否刚刚安装到系统上。如果有，脚本打印消息“MyApplicationName刚刚安装”并结束(返回1意味着以“错误”结束，不是吗?)
如果用户要求Debian/Ubuntu包系统安装我的包，脚本还会删除两个目录。
是这样吗，还是我漏掉了什么?
set -e该选项指示bash在任何命令[1]的退出状态为非零时立即退出。您可能不想为命令行shell设置这个，但在脚本中它非常有用。在所有广泛使用的通用编程语言中，一个未处理的运行时错误——无论是Java中的抛出异常，还是C中的分段错误，或者Python中的语法错误——都会立即停止程序的执行;后续行不执行。
By default, bash does not do this. This default behavior is exactly what you want if you are using bash on the command line
you don't want a typo to log you out! But in a script, you really want the opposite.
If one line in a script fails, but the last line succeeds, the whole script has a successful exit code. That makes it very easy to miss the error.
Again, what you want when using bash as your command-line shell and using it in scripts are at odds here. Being intolerant of errors is a lot better in scripts, and that's what set -e gives you.
复制自:https://gist.github.com/mohanpedala/1e2ff5661761d3abd0385e8223e16425
这可能对你有帮助。
cat a.sh
#! /bin/bash
#going forward report subshell or command exit value if errors
#set -e
(cat b.txt)
echo "hi"
./a.sh; echo $?
cat: b.txt: No such file or directory
hi
0
当set -e被注释掉时，我们看到echo "hi"退出状态被报告，hi被打印出来。
cat a.sh
#! /bin/bash
#going forward report subshell or command exit value if errors
set -e
(cat b.txt)
echo "hi"
./a.sh; echo $?
cat: b.txt: No such file or directory
1
现在我们看到b.txt错误被报告，没有打印hi。
因此shell脚本的默认行为是忽略命令错误并继续处理并报告最后一个命令的退出状态。如果你想退出错误并报告它的状态，我们可以使用-e选项。
